Conventional gear wrenches featuring reversible function are provided with a direction switch button on a single side of the wrench. With the fast development of technology, the reduced or compact sizes of many components have reduced space for maneuver around the components, such as within the packed space in a vehicular engine room, rendering inconvenience in operation of hand tools. As shown in FIGS. 8A and 8B, when an operator intends to switch the operative direction of the wrench after inserting a wrench into a packed space, due to the lack of space for maneuver around the direction switches CB, CA, the operator must withdraw the wrench first for adjusting the operative direction, which is very time-consuming. A gear wrench allowing an operator to switch the operative direction a gear ring from either side of the wrench (such as that illustrated in FIGS. 9A and 9B) will, thus, significantly increase the efficiency.